#!/usr/bin/python2.2
"""HTML Diff: http://www.aaronsw.com/2002/diff
Rough code, badly documented. Send me comments and patches."""

__author__ = 'Aaron Swartz <me@aaronsw.com>'
__copyright__ = '(C) 2003 Aaron Swartz. GNU GPL 2.'
__version__ = '0.22'

import difflib, string

def isTag(x): return x[0] == "<" and x[-1] == ">"

def textDiff(a, b):
  """Takes in strings a and b and returns a human-readable HTML diff."""

  out = []
  a, b = html2list(a), html2list(b)
  s = difflib.SequenceMatcher(None, a, b)
  for e in s.get_opcodes():
    if e[0] == "replace":
      # @@ need to do something more complicated here
      # call textDiff but not for html, but for some html... ugh
      # gonna cop-out for now
      out.append('<del class="diff modified">'+''.join(a[e[1]:e[2]]) + \
                 '</del><ins class="diff modified">'+''.join(b[e[3]:e[4]])+"</ins>")
    elif e[0] == "delete":
      out.append('<del class="diff">'+ ''.join(a[e[1]:e[2]]) + "</del>")
    elif e[0] == "insert":
      out.append('<ins class="diff">'+''.join(b[e[3]:e[4]]) + "</ins>")
    elif e[0] == "equal":
      out.append(''.join(b[e[3]:e[4]]))
    else: 
      raise "Um, something's broken. I didn't expect a '" + `e[0]` + "'."
  return ''.join(out)

def html2list(x, b=0):
  """ Hier wird verglichen """
  mode = 'char'
  cur = ''
  out = []
  for c in x:
    if mode == 'tag':
      if c == '>': 
        if b: cur += ']'
        else: cur += c
        out.append(cur); cur = ''; mode = 'char'
      else: cur += c
    elif mode == 'char':
      if c == '<': 
        out.append(cur)
        if b: cur = '['
        else: cur = c
        mode = 'tag'
      elif c in string.whitespace: out.append(cur+c); cur = ''
      else: cur += c
  out.append(cur)
  return filter(lambda x: x is not '', out)

"""
if __name__ == '__main__':
  import sys
  try:
    a, b = sys.argv[1:3]
  except ValueError:
    print "htmldiff: highlight the differences between two html files"
    print "usage: " + sys.argv[0] + " a b"
    sys.exit(1)
  print textDiff(open(a).read(), open(b).read())
"""
